dorsal surface, in vivo

Description:

Dorsal surface of the frontoniid ciliate, Disematostoma buetschlii LAUTERBORN, 1894. D. buetschlii contains endosymbiotic algae but may lose (or digest) them during fall and winter (Ulrike-G.Berninger, Bland J.Finlay, and Hilda M.Canter; The Spatial Distribution and Ecology of Zoochlorellae-Bearing Ciliates in a Productive Pond. J.Protozool. 33(4):557-563, 1986). Although this specimen is slightly smaller (80 microns) than what is commonly reported for D. buetschlii (about 110 microns) it is otherwise indistinguishable. Kahl describes a smaller species without endosymbiotic algae (D. minor) (A.Kahl; [Urtiere oder Protozoa I: Wimpertiere oder Ciliata (Infusoria) 2. Holotricha]. Die Tierwelt Deutschlands und der angrenzenden Meeresteile. Germany:Verlag von Gustav Fischer. (2)-398). However it is unclear whether this is simply a small variety of D. buetschlii without algal endosymbionts. The cell shape is obovoid tapering to a blunt slightly curved point posteriorly. Dorsal surface convex with a flattened ventral surface. The cytostome is located in the anterior 1/3 with 3 left adoral membranelles and an inconspicuous undulating membrane on the right. 4-5 dense vestibular ciliary rows are found on the right of the cytostome. The reniform macronucleus is seen well here. The longitudinal somatic kineties terminate on prominent ladder-like preoral and postoral suture (the polar band). The polar band can be seen curving to the viewer's right in this image. The solitary dorsal excretory pore of the contractile vacuole is seen here to the viewer's right of the anterior part of the polar band.D. buetschlii is primarily algivorous and some of the green algae seen in the cytoplasm in this image may be in food vacuoles. Collected from freshwater pond near Boise, Idaho September 2003. DIC.